Shahi Pawan Kumar, Choi Seok, Zuo Dong Chuan, Kim Man Yoo, Park Chan Guk, Kim Young Dae, Lee Jun, Park Kyu Joo, So Insuk, Jun Jae Yeoul
Department of Physiology, College of Medicine, Chosun University, Sesuk-dong, Dong-gu, Gwangju, 501-759, Korea.
J Gastroenterol. 2014 Jun;49(6):1001-10. doi: 10.1007/s00535-013-0849-3. Epub 2013 Jun 19.
Hyperpolarization-activated cyclic nucleotide (HCN) channels are pacemaker channels that regulate heart rate and neuronal rhythm in spontaneously active cardiac and neuronal cells. Interstitial cells of Cajal (ICCs) are also spontaneously active pacemaker cells in the gastrointestinal tract. Here, we investigated the existence of HCN channel and its role on pacemaker activity in colonic ICCs.
We performed whole-cell patch clamp, RT-PCR, and Ca(2+)-imaging in cultured ICCs from mouse mid colon.
SQ-22536 and dideoxyadenosine (adenylate cyclase inhibitors) decreased the frequency of pacemaker potentials, whereas both rolipram (cAMP-specific phosphodiesterase inhibitor) and cell-permeable 8-bromo-cAMP increased the frequency of pacemaker potentials. CsCl, ZD7288, zatebradine, clonidine (HCN channel blockers), and genistein (a tyrosine kinase inhibitor) suppressed the pacemaker activity. RT-PCR revealed expression of HCN1 and HCN3 channels in c-kit and Ano1 positive colonic ICCs. In recordings of spontaneous intracellular Ca(2+) [Ca(2+)]i oscillations, rolipram and 8-bromo-cAMP increased [Ca(2+)]i oscillations, whereas SQ-22536, CsCl, ZD7288, and genistein decreased [Ca(2+)]i oscillations.
HCN channels in colonic ICCs are tonically activated by basal cAMP production and participate in regulation of pacemaking activity.
超极化激活环核苷酸（HCN）通道是调节自发活动的心脏和神经元细胞心率及神经元节律的起搏通道。 Cajal间质细胞（ICC）也是胃肠道中自发活动的起搏细胞。在此，我们研究了HCN通道在结肠ICC中的存在及其对起搏活动的作用。
我们对从小鼠结肠中段培养的ICC进行了全细胞膜片钳、逆转录聚合酶链反应（RT-PCR）和Ca(2+)成像。
SQ-22536和双脱氧腺苷（腺苷酸环化酶抑制剂）降低了起搏电位的频率，而咯利普兰（cAMP特异性磷酸二酯酶抑制剂）和细胞可渗透的8-溴-cAMP均增加了起搏电位的频率。氯化铯、ZD7288、扎替雷定、可乐定（HCN通道阻滞剂）和染料木黄酮（一种酪氨酸激酶抑制剂）抑制了起搏活动。RT-PCR显示HCN1和HCN3通道在c-kit和Ano1阳性的结肠ICC中表达。在自发细胞内Ca(2+) [Ca(2+)]i振荡记录中, 咯利普兰和8-溴-cAMP增加了[Ca(2+)]i振荡，而SQ-22536、氯化铯、ZD7288和染料木黄酮降低了[Ca(2+)]i振荡。
结肠ICC中的HCN通道被基础cAMP产生持续激活，并参与起搏活动的调节。
